Some states place restrictions on hunters regarding such things as type of animal, gender of the animal, the size of the animal, and so on, that a hunter may be permitted to kill in a given hunting season. Further, some states also require the particular prey to have a certain antler characteristics, such as, the number of points on its antlers. It may be difficult to determine, from a distance, whether a particular target can be shot under the particular state's hunting regulations.
In addition to regulatory considerations, some hunters may also want additional information or verification that an animal that he/she is hunting is above a pre-determined level in terms of a trophy specimen. As a hunter approaches his or her limit, he or she may wish to be more selective in terms of target selection. In a particular example, a hunter may elect to hunt for a trophy specimen, such as a deer that would qualify on the Boone and Crockett® scale (for guns) or on the Pope and Young® scale (for bows). However, even experienced hunters may struggle to estimate the relative value of a given target, particularly at an unknown distance. Unfortunately, to determine a prey score for a particular target, a hunter often has to kill the animal and then perform a series of measurements.